1. Field of the Invention
The present invention relates to a power-saving control apparatus for electronic equipment (a main apparatus).
2. Description of the Related Art
In authentication using S/Key (registered trademark) described in reference 1 (Haller, N., “The S/KEY One•Time Password System”, ISOC, 1994), which is a one-time password scheme which changes an authentication code every time authentication succeeds, an authentication code is always synchronized to feed back authentication OK/NG from an authentication apparatus to an authentication target apparatus. When, however, authentication is performed by a one-time password scheme such as S/Key (registered trademark) in a case in which only one-way communication from an authentication target apparatus to an authentication apparatus (the power-saving control apparatus) can be performed, since there is no synchronization means (a means for transmitting an acknowledgement indicating the success of authentication from the authentication apparatus to the authentication target apparatus), an authentication code may lose synchronization.
In order to correct a synchronization loss (=time offset), one-time password authentication based on a time synchronization scheme uses a method of holding, in advance, candidates of a plurality of authentication codes by which an authentication apparatus determines authentication OK. For example, there is available SecurID (registered trademark) as an authentication token available from RSA Security disclosed in reference 2 (“RSA SecurID”, [online], [searched on Oct. 26, 2007], Internet <URL: http://www.rsa.com/node.aspx?id=1156>).
When, however, the power-saving control apparatus is to perform collation with many authentication codes, the circuit size and power consumption increase. When an apparatus designed to perform signal collation using a very weak power of nearly “0” is to perform collation with a plurality of authentication codes, the number of authentication codes to be verified needs to be minimized to minimize the circuit size and power consumption.
As described above, there has been the problem that performing collation with many authentication codes results in increases in circuit size and power consumption.